Technical Field
Embodiments of the present invention generally relate to a developing device for use in an electrophotographic image forming apparatus such as a photocopier, a facsimile machine, a printer, or a multifunction peripheral (MFP) having at least two of copying, printing, facsimile transmission, plotting, and scanning capabilities, and the image forming apparatus and a process cartridge including the developing device.
Description of the Related Art
There are multistage developing devices that includes multiple developer bearers (e.g., developing rollers) arranged in the direction of rotation of an image bearer (e.g., a photoconductor drum) and disposed facing the image bearer.
For example, there are developing devices that employ two-component developer including toner and carrier (in which one or more additives may be included) and includes two developing rollers. A portion of developer contained in the developing device is supplied to a first developing roller on the upstream side in the direction of rotation of the photoconductor drum. A doctor blade (i.e., a developer regulator) regulates the amount of developer on the first developing roller. When the first developing roller rotates and the developer on the first developing roller reaches a position facing the photoconductor drum (i.e., a first developing range), the toner in the developer is electrostatically attracted to a latent image on the photoconductor drum. Then, the developer on the first developing roller is, partly or entirely, supplied to a second developing roller on the downstream side. When the second developing roller rotates and the developer on the second developing roller reaches a position facing the photoconductor drum (i.e., a second developing range different from the first developing range), the toner in the developer is electrostatically attracted to the latent image on the photoconductor drum.
Such multistage developing devices excel in developing capability and provide high-quality images since the multiple developing rollers extend the duration of the developing process.